Three dimensional shape measurement apparatus and method

ABSTRACT

A three dimensional shape measurement apparatus includes m projecting sections, each of which includes a light source and a grating element, and, while moving the grating element by n times, projects a grating pattern light onto a measurement target for each movement, wherein the ‘n’ and the ‘m’ are natural numbers greater than or equal to 2, an imaging section photographing a grating pattern image reflected by the measurement target, and a control section controlling that, while photographing the grating pattern image by using one of the m projecting sections, a grating element of at least another projecting section is moved. Thus, measurement time may be reduced.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority from and the benefit of Korean PatentApplications No. 2009-46669 filed on May 27, 2009, No. 2009-46671 filedon May 27, 2009, No. 2010-23521 filed on Mar. 16, 2010, and No.2010-47920 filed on May 24, 2010, which are hereby incorporated byreference for all purposes as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Exemplary embodiments of the present invention relate to a threedimensional shape measurement apparatus and a method of measuring athree dimensional shape. More particularly, exemplary embodiments of thepresent invention relate to a three dimensional shape measurementapparatus and a method of measuring a three dimensional shape capable ofreducing measurement time.

2. Discussion of the Background

Generally, a three dimensional shape measurement apparatus measures athree dimensional shape of a measurement target by using a photographedimage. The three dimensional shape measurement apparatus may include aprojecting section illuminating light to the measurement target, acamera section photographing an image by using the light reflected bythe measurement target, and a control section controlling the projectingsection and the camera section and arithmetically processing the imageto measure the three dimensional shape.

As described above, since the three dimensional shape measurementapparatus arithmetically processes the photographed image of themeasurement target to measure the three dimensional shape, reducingmeasurement time for the three dimensional shape of the measurementtarget enhances rapidity and efficiency of work, to thereby reducemeasurement cost. Thus, the measurement time is very important factor.

In a conventional three dimensional shape measurement apparatus, thefollowing examples may be factors increasing the above mentionedmeasurement time.

First, the measurement time increases according to a photographingmethod and a grating-moving method.

FIG. 1 is a block diagram illustrating a method of measuring a threedimensional shape using a conventional three dimensional shapemeasurement apparatus.

Referring to FIG. 1, when using two projecting sections, conventionally,a plurality of images is photographed while a grating of a firstprojecting section is moved, and then a plurality of images isphotographed while a grating of a second projecting section is moved.

However, since a grating is moved after photographing of camera,photographing time and movement time of the grating are independentlyrequired. Thus, total measurement time increases, and more increases asthe number of the projecting sections increases.

Second, when a measurement target having a relatively large area isdivided into a plurality of measurement areas and measured, longmeasurement time is required.

In case that images are photographed for each measurement area withrespect to the measurement target having a relatively large area, and athree dimensional shape of the measurement target is measured by usingthe images, it is required that the camera section photographs an imagefor any one measurement area, and thereafter the image is arithmeticallyprocessed to measure a three dimensional shape in the measurement area.

However, in case that arithmetical process for the photographed imagebecomes a little longer, it may take a long time that a measurementtarget area is moved to each measurement area of the measurement targetand in addition, the three dimensional shape measurement apparatusmeasures three dimensional shapes of all the measurement areas.

Third, it is limited to reducing photographing time of a camera andmoving time of a grating element.

In order to rapidly inspect a board, it is required that photographingtime of a camera and moving time of a grating element is reduced.However, when photographing time of a camera is reduced, a reflectiongrating image is not sufficiently received to thereby prevent accurateinspection. In addition, moving time of a grating element is verylimited. Thus, it is difficult to substantially reduce inspection time.

Fourth, in case that a measurement target has a relatively small size,measurement time needlessly increases.

In order to inspect a measurement target having a relatively small size,for example, an LED bar, a plurality of measurement targets is inspectedin a status that the measurement targets are mounted on an inspectionboard such as a jig. Thus, both a portion in which the measurementtargets exist and a portion in which the measurement targets do notexist are in a field of view of a camera.

Accordingly, when image data are acquired for all the areas in the fieldof view of the camera, and the image data are processed, unnecessarydata process is performed for the portion in which the measurementtargets do not exist, to increase data processing time and therebyincrease measurement time.

SUMMARY OF THE INVENTION

Exemplary embodiments of the present invention provide a threedimensional shape measurement apparatus capable of reducing measurementtime for a three dimensional shape.

Exemplary embodiments of the present invention also provide a method ofmeasuring a three dimensional shape capable of reducing measurement timefor a three dimensional shape.

Exemplary embodiments of the present invention also provide a boardinspection apparatus and a method of inspecting a board using the boardinspection apparatus capable of reducing measurement time and enhancingmeasurement quality.

Exemplary embodiments of the present invention also provide a method ofmeasuring a three dimensional shape capable of selectively measuringonly an area in which measurement targets exist to reduce measurementtime.

An exemplary embodiment of the present invention discloses a threedimensional shape measurement apparatus. The three dimensional shapemeasurement apparatus includes m projecting sections, each of whichincludes a light source and a grating element, and, while moving thegrating element by n times, projects a grating pattern light onto ameasurement target for each movement, wherein the ‘n’ and the ‘m’ arenatural numbers greater than or equal to 2, an imaging sectionphotographing a grating pattern image reflected by the measurementtarget, and a control section controlling that, while photographing thegrating pattern image by using one of the m projecting sections, agrating element of at least another projecting section is moved.

When the m is 2, while photographing the grating pattern image by onetime by using a first projecting section, the control section may movethe grating element of a second projecting section by 2π/n, and thenwhile photographing the grating pattern image by one time by using thesecond projecting section, the control section may move the gratingelement of the first projecting section by 2π/n.

When the m is greater than or equal to 3, the control section mayphotograph the grating pattern image by m times by using the projectingsections for one time respectively, from a first projecting section toan m-th projecting section, and a grating element of a projectingsection that is not used for the photographing time of the m times maybe moved by 2π/n for non-photographing time. The control section maycontrol that each projecting section moves the grating element thereofbefore at least two photographing times prior to projecting the gratingpattern light.

The control section may control that the grating pattern image isphotographed by using one projecting section of the m projectingsections, and then for immediately following photographing time ofanother projecting section, a grating element of the one projectingsection is moved.

An exemplary embodiment of the present invention discloses a method ofmeasuring a three dimensional shape. The method includes photographing afirst image in a first measurement area of a measurement target,arithmetically processing the first image by a first central processingunit to produce a three dimensional shape in the first measurement area,photographing a second image in a second measurement area of themeasurement target while the first central processing unitarithmetically processes the first image, and arithmetically processingthe second image by a second central processing unit to produce a threedimensional shape in the second measurement area.

The method may further include photographing a third image in a thirdmeasurement area of the measurement target while arithmeticallyprocessing the second image by the second central processing unit, andarithmetically processing the third image by the first centralprocessing unit to produce a three dimensional shape in the thirdmeasurement area.

Each of the first and second images may include a plurality of wayimages photographed with respect to the measurement target in differentdirections. Arithmetically processing each of the first and secondimages may be performed by arithmetically processing each imageindependently, and merging arithmetically processed data for the firstand second images.

An exemplary embodiment of the present invention discloses a method ofmeasuring a three dimensional shape. The method includes photographing afirst image in a first measurement area of a measurement target in afirst direction and a second direction, photographing a second image ina second measurement area of the measurement target at least in thefirst direction and the second direction, after photographing the firstimage, and dividing the first image into an image corresponding to thefirst direction and an image corresponding to the second direction andarithmetically processing the divided images by a plurality of centralprocessing units, to produce a three dimensional shape in the firstmeasurement area.

The central processing units may include a first central processing unitarithmetically processing the image corresponding to the first directionand a second central processing unit arithmetically processing the imagecorresponding to the second direction. At least one of the first andsecond central processing units may merge the arithmetically processeddata for the image corresponding to the first direction and the imagecorresponding to the second direction.

Dividing the first image and arithmetically processing the dividedimages to produce the three dimensional shape may include dividing thefirst image into a plurality of segments and arithmetically processingthe divided segments by the central processing units.

An exemplary embodiment of the present invention discloses a boardinspection apparatus. The board inspection apparatus includes a stagesupporting a board, a projecting section including a light source and agrating element, the projecting section illuminating a grating patternlight onto the board, and a camera sequentially opened from a first lineto a last line to receive a reflection grating image reflected by theboard. The grating element is moved for at least time interval for whichthe camera is opened from the first line to the last line.

The grating element may be not moved for a time interval for which alllines of the camera simultaneously receive the reflection grating image.The grating pattern light may be illuminated by the projection sectionfor a predetermined time interval existing between a time at which thelast line is opened and a time at which the first line is closed. Thegrating element may be moved by 2π/n per one time and n−1 times intotal, and the camera may receive the reflection grating image by ntimes corresponding to movement of the grating element, wherein the ‘n’is a natural number greater than or equal to 2.

An exemplary embodiment of the present invention discloses a method ofinspecting a board by using at least two projecting sections, each ofwhich includes a light source and a grating element, and a camera. Themethod includes sequentially opening the camera from a first line to alast line, illuminating a grating pattern light onto the board by usinga first projecting section of the projecting sections, and moving agrating element included in at least one second projecting sectiondifferent from the first projecting section for a predetermined timeinterval existing between a time at which the last line is opened and atime at which the last line is closed.

The first projecting section may illuminate the grating pattern lightfor a predetermined time interval existing between a time at which thelast line is opened and a time at which the first line is closed.

An exemplary embodiment of the present invention discloses a method ofinspecting a board. The method includes loading an inspection board onwhich a plurality of measurement targets are disposed to an inspectionapparatus, dividing inspection areas in which the measurement targetsare located in a field of view of a camera to acquire image data foreach inspection area, and inspecting shapes of the measurement targetsby using the acquired image data for each inspection area.

Dividing the inspection areas to acquire the image data may includeilluminating a pattern light onto the measurement targets, and receivingreflection pattern lights reflected by the measurement targets by usingthe camera.

The measurement targets may correspond to boards disposed in a pluralityof rows with a predetermined direction. The inspection board maycorrespond to a fixing supporter fixing the measurement targets.

Inspecting the shapes of the measurement targets may include mapping theacquired image data for each inspection area to generate a total imageof each measurement target.

According to the present invention, photographing of a camera andmovement of a grating is simultaneously performed, to thereby greatlyreducing measurement time for a three dimensional shape. Also, thanks toreduction of measurement time, photographing time of the camera may besufficiently increased to secure light amount required forphotographing.

In addition, multiple images are arithmetically processed by using aplurality of central processing units to thereby increase processingspeed for the images.

In addition, in moving a grating element by using one projecting sectionand a camera, and photographing a plurality of phase-transited images,the grating element is moved for rolling time of the camera for whichphotographing an image is not performed, to thereby reduce measurementtime.

In addition, in photographing an image of a measurement target by usingat least two projecting sections, the grating element is moved for aframe interval for which an associated projecting section does notilluminate light, to thereby more reduce measurement time.

In addition, in measuring an inspection board on which a plurality ofmeasurement targets are mounted, only an inspection area in which themeasurement targets are located is measured, to thereby reducephotographing time of a camera.

In addition, image data for only an inspection area are used, dataamount required to be processed may be reduced, and especially, dataamount for comparison in image-mapping may be reduced to greatly reducemeasurement time.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention, andtogether with the description serve to explain the principles of theinvention.

FIG. 1 is a block diagram illustrating a method of measuring a threedimensional shape using a conventional three dimensional shapemeasurement apparatus.

FIG. 2 is a schematic view illustrating a three dimensional shapemeasurement apparatus according to an exemplary embodiment of thepresent invention.

FIG. 3 is a block diagram illustrating a method of driving a threedimensional shape measurement apparatus including two projectingsections according to an exemplary embodiment of the present invention.

FIG. 4 is a block diagram illustrating a method of driving a threedimensional shape measurement apparatus including two projectingsections according to an exemplary embodiment of the present invention.

FIG. 5 is a schematic view illustrating a three dimensional shapemeasurement apparatus according to an exemplary embodiment of thepresent invention.

FIGS. 6 and 7 are block diagrams illustrating a method of arithmeticallyprocessing multiple images according to an exemplary embodiment of thepresent invention.

FIG. 8 is a block diagram illustrating a process of arithmeticallyprocessing multiple images by using a single CPU.

FIG. 9 is a block diagram illustrating a method of arithmeticallyprocessing multiple images according to an exemplary embodiment of thepresent invention.

FIG. 10 is a block diagram illustrating a method of arithmeticallyprocessing multiple images according to an exemplary embodiment of thepresent invention.

FIG. 11 is a schematic view illustrating a board inspection apparatusaccording to an exemplary embodiment of the present invention.

FIG. 12 is a time chart illustrating a method of inspecting a boardaccording to an exemplary embodiment of the present invention.

FIG. 13 is a time chart illustrating a method of inspecting a boardaccording to an exemplary embodiment of the present invention.

FIG. 14 is a schematic view illustrating a board inspection apparatusaccording to an exemplary embodiment of the present invention.

FIG. 15 is a flow chart illustrating a method of inspecting a boardaccording to an exemplary embodiment of the present invention.

FIG. 16 is a plan view illustrating an inspection board according to anexemplary embodiment of the present invention.

FIG. 17 is a plan view illustrating a partial image of the inspectionboard in FIG. 16, which is photographed by a camera.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

The present invention is described more fully hereinafter with referenceto the accompanying drawings, in which example embodiments of thepresent invention are shown. The present invention may, however, beembodied in many different forms and should not be construed as limitedto the example embodiments set forth herein. Rather, these exampleembodiments are provided so that this disclosure will be thorough andcomplete, and will fully convey the scope of the present invention tothose skilled in the art. In the drawings, the sizes and relative sizesof layers and regions may be exaggerated for clarity.

It will be understood that when an element or layer is referred to asbeing “on,” “connected to” or “coupled to” another element or layer, itcan be directly on, connected or coupled to the other element or layeror intervening elements or layers may be present. In contrast, when anelement is referred to as being “directly on,” “directly connected to”or “directly coupled to” another element or layer, there are nointervening elements or layers present. Like numerals refer to likeelements throughout. As used herein, the term “and/or” includes any andall combinations of one or more of the associated listed items.

It will be understood that, although the terms first, second, third etc.may be used herein to describe various elements, components, regions,layers and/or sections, these elements, components, regions, layersand/or sections should not be limited by these terms. These terms areonly used to distinguish one element, component, region, layer orsection from another region, layer or section. Thus, a first element,component, region, layer or section discussed below could be termed asecond element, component, region, layer or section without departingfrom the teachings of the present invention.

Spatially relative terms, such as “beneath,” “below,” “lower,” “above,”“upper” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, the exemplary term “below” can encompass both anorientation of above and below. The device may be otherwise oriented(rotated 90 degrees or at other orientations) and the spatially relativedescriptors used herein interpreted accordingly.

The terminology used herein is for the purpose of describing particularexample embodiments only and is not intended to be limiting of thepresent invention. As used herein, the singular forms “a,” “an” and“the” are intended to include the plural forms as well, unless thecontext clearly indicates otherwise. It will be further understood thatthe terms “comprises” and/or “comprising,” when used in thisspecification, specify the presence of stated features, integers, steps,operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, elements, components, and/or groups thereof.

Example embodiments of the invention are described herein with referenceto cross-sectional illustrations that are schematic illustrations ofidealized example embodiments (and intermediate structures) of thepresent invention. As such, variations from the shapes of theillustrations as a result, for example, of manufacturing techniquesand/or tolerances, are to be expected. Thus, example embodiments of thepresent invention should not be construed as limited to the particularshapes of regions illustrated herein but are to include deviations inshapes that result, for example, from manufacturing. For example, animplanted region illustrated as a rectangle will, typically, haverounded or curved features and/or a gradient of implant concentration atits edges rather than a binary change from implanted to non-implantedregion. Likewise, a buried region formed by implantation may result insome implantation in the region between the buried region and thesurface through which the implantation takes place. Thus, the regionsillustrated in the figures are schematic in nature and their shapes arenot intended to illustrate the actual shape of a region of a device andare not intended to limit the scope of the present invention.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

Hereinafter, exemplary embodiments of the present invention will bedescribed in detail with reference to the accompanying drawings.

FIG. 2 is a schematic view illustrating a three dimensional shapemeasurement apparatus according to an exemplary embodiment of thepresent invention.

Referring to FIG. 2, a three dimensional shape measurement apparatus 100according to an exemplary embodiment of the present invention includesprojecting sections 110, the number of which is ‘m’, an imaging section120 and a control section 130. The ‘m’ is a natural number greater thanor equal to 2.

Each of the m projecting sections 110 projects a grating pattern lightonto a measurement target 150 that is fixed to a work stage 140. Theprojecting sections 110 may be disposed to illuminate grating patternlights inclined with respect to a normal line of the measurement target150 by a predetermined angle. For example, the three dimensional shapemeasurement apparatus 100 may include 2, 3, 4 or 6 projecting sections110, and the plurality of the projecting sections 110 may besymmetrically disposed with respect to the normal line of themeasurement target 150.

Each of the projecting sections 110 includes a light source 111 and agrating element 112. Each projecting section 110 may further include aprojecting lens part 113. The light source 111 illuminates light towardthe measurement target 150. The grating element 112 converts the lightgenerated from the light source 111 into the grating pattern lightaccording to a grating pattern thereof. The grating element 112 is movedusing a grating-moving instrument (not shown) such as an actuator by2π/n per one time and n times in total to generate the grating patternlight that is phase-transited. The ‘n’ is a natural number greater thanor equal to 2. The projecting lens part 113 projects the grating patternlight generated by the grating element 112 onto the measurement target150. The projecting lens part 113 may include, for example, combinationof a plurality of lenses, and focuses the grating pattern lightgenerated by the grating element 112 to project the focused gratingpattern light onto the measurement target 150. Thus, each projectingsection 110 projects the grating pattern light onto the measurementtarget 150 for each movement while the grating element 112 is moved by ntimes.

The imaging section 120 photographs a grating pattern image that isreflected from the measurement target 150 by the grating pattern lightprojected onto the measurement target 150. Since the three dimensionalshape measurement apparatus 100 includes m projecting sections 110, andphotographing is performed by n times with respect to each projectingsection 110, the imaging section 120 photographs the grating patternimage by n×m times. The imaging section 120 may include a camera 121 andan imaging lens part 122 so as to photograph the grating pattern image.The camera 121 may employ a CCD or a CMOS camera. Thus, the gratingpattern image reflected by the measurement target 150 is photographed bythe camera 121 via the imaging lens part 122.

The control section 130 generally controls the components included inthe three dimensional shape measurement apparatus 100. The controlsection 130 moves the grating element 112 by n times, and controls theprojecting section 110 to project the grating pattern light onto themeasurement target 150 for each movement. In addition, the controlsection 130 controls the imaging section 120 to photograph the gratingpattern image reflected by the measurement target 150.

In order to reduce total measurement time of the three dimensional shapemeasurement apparatus 100, while photographing the grating pattern imageby using one of the m projecting sections 110, the control section 130controls the grating element 112 of at least one another projectingsection 110 to move. For example, the grating pattern image isphotographed by using one projecting section 110 of the m projectingsections 110, and then for immediately following photographing time ofanother projecting section 110, the control section 130 may move thegrating element 112 of the one projecting section 110 by 2π/n.

FIG. 3 is a block diagram illustrating a method of driving a threedimensional shape measurement apparatus including two projectingsections according to an exemplary embodiment of the present invention.

Referring to FIGS. 2 and 3, the three dimensional shape measurementapparatus 100 according to an exemplary embodiment of the presentinvention includes two projecting sections 110, for example, a firstprojecting section 110 a and a second projecting section 110 b.

The control section 130 moves the grating element 112 of the secondprojecting section 110 b by a distance corresponding to a phase of 2π/n,while photographing a grating pattern image 1 by one time by using thefirst projecting section 110 a. Then, the control section 130 moves thegrating element 112 of the first projecting section 110 a by a distancecorresponding to a phase of 2π/n, while photographing a grating patternimage 2 by one time by using the second projecting section 110 b. Inother words, the grating pattern image 1 is photographed by using thefirst projecting section 110 a, and then for immediately followingphotographing time of the second projecting section 110 b, the controlsection 130 moves the grating element 112 of the first projectingsection 110 a. Then, the control section 130 repeats the above processesby using the first projecting section 110 a and the second projectingsection 110 b to control photographing of a grating pattern image 3 to agrating pattern image 8.

Thereafter, the control section 130 combines the grating pattern images1, 3, 5 and 7 photographed by using the first projecting section 110 ato acquire first phase information, and combines the grating patternimages 2, 4, 6 and 8 photographed by using the second projecting section110 b to acquire second phase information, and then the threedimensional shape of the measurement target 150 is measured by using thefirst phase information and the second phase information.

As described above, when photographing of the camera and moving of thegrating is simultaneously performed, measurement time is greatly reducedin comparison with a method described in FIG. 1. In addition, thanks toreduction of measurement time, photographing time of the camera may besufficiently increased, to thereby make it possible to acquire lightamount required for photographing.

In FIG. 3, for example, a 4-bucket method is described, in whichphotographing is performed by four times for each projecting section110. Alternatively, the above method may be applied to various bucketmethods such as 3-bucket.

Meanwhile, when the three dimensional shape measurement apparatus 100includes three or more projecting sections 110, the control section 130controls photographing of the grating pattern image by m times, by usingthe projecting sections for one time respectively, from a firstprojecting section to a final projecting section, i.e., an m-thprojecting section, and simultaneously, a grating element of aprojecting section that is not used for the photographing time of the mtimes is moved by 2π/n for the non-photographing time. For example, adriving method will be described with reference to FIG. 4, for a casethat a three dimensional shape measurement apparatus includes threeprojecting sections.

FIG. 4 is a block diagram illustrating a method of driving a threedimensional shape measurement apparatus including two projectingsections according to an exemplary embodiment of the present invention.

Referring to FIG. 4, a three dimensional shape measurement apparatus mayinclude three projecting sections, for example, a first projectingsection, a second projecting section and a third projecting section. Forexample, three projecting sections may be disposed apart from each otherby an angle of 120 degrees with respect to the center of the measurementtarget.

While photographing a grating pattern image 1 by using the firstprojecting section of the three projecting sections, a grating elementof one of the remaining projecting sections, for example, the thirdprojecting section is moved by a distance corresponding to a phase of2π/n. Then, while photographing a grating pattern image 2 by using thesecond projecting section, a grating element of one of the remainingprojecting sections, for example, the first projecting section is movedby a distance corresponding to a phase of 2π/n. Thereafter, whilephotographing a grating pattern image 3 by using the third projectingsection, a grating element of one of the remaining projecting sections,for example, the second projecting section is moved by a distancecorresponding to a phase of 2π/n. Then, the above processes are repeatedby using the first projecting section, the second projecting section andthe third projecting section to photograph a grating pattern image 4 toa grating pattern image 12.

Thanks to reduction of photographing time, movement time of the gratingelement may be relatively increased. For example, when the photographingtime is about 5 ms, and the movement time of the grating element isabout 7 ms, the movement time of the grating element becomes longer thanthe photographing time by about 2 ms. Thus, since the grating element isnot movable within one photographing time, the movement of the gratingelement is moved for two photographing times. Accordingly, before atleast two photographing times prior to projecting the grating patternlight, each projecting section may preferably move the grating elementthereof. For example, before photographing the grating pattern image 4,the first projecting section may preferably move the grating elementthereof for two photographing times of the grating pattern image 2 andthe grating pattern image 3. To this end, each projecting section maypreferably move the grating element thereof, directly afterphotographing the grating pattern image.

After completing photographing the grating pattern image 1 to thegrating pattern image 12, the grating pattern images 1, 4, 7 and 10photographed by using the first projecting section are combined toacquire first phase information, the grating pattern images 2, 5, 8 and11 photographed by using the second projecting section are combined toacquire second phase information, and the grating pattern images 3, 6, 9and 12 photographed by using the third projecting section are combinedto acquire third phase information. Then, the three dimensional shape ofthe measurement target is measured by using the first phase information,the second phase information and the third phase information.

In FIG. 4, for example, a 4-bucket method is described, in whichphotographing is performed by four times for each projecting section.Alternatively, the above method may be applied to various bucket methodssuch as 3-bucket. In addition, the method in FIG. 4 may be applied to athree dimensional shape measurement apparatus including four or moreprojecting sections.

FIG. 5 is a schematic view illustrating a three dimensional shapemeasurement apparatus according to an exemplary embodiment of thepresent invention.

Referring to FIG. 5, a three dimensional shape measurement apparatus 300according to an exemplary embodiment of the present invention includes aprojecting section 310, a camera section 320 and a control section 330.For example, the three dimensional shape measurement apparatus 300measures a three dimensional shape of a predetermined measurement target20 formed on a base board 10.

The projecting section 310 is disposed over the base board 10 toilluminate a light onto the measurement target 20 formed on the baseboard 10. The projecting section 310 includes at least one illuminationunit, and for example, may include a first illumination unit 312 and asecond illumination unit 314.

The first illumination unit 312 is disposed over the base board 10 toilluminate a first light in a first direction inclined with respect tothe measurement target 20. The second illumination unit 314 illuminatesa second light in a second direction symmetrical to the first directionwith respect to the base board 10.

Particularly, the first illumination unit 312 may illuminate a firstgrating pattern light toward the measurement target 20, and the secondillumination unit 314 may illuminate a second grating pattern lighttoward the measurement target 20.

In an exemplary embodiment, each of the first and second illuminationunits 312 and 314 may include a light source (not shown) generatinglight, a grating unit through which the light from the light sourcepasses to form the first grating pattern light or the second gratingpattern light, and a projecting lens (not shown) projecting the firstgrating pattern light or the second grating pattern light on themeasurement target 20.

The grating unit may have various forms. For example, a grating patternhaving a shielding portion and a transmitting portion may be patternedon a glass substrate to form the grating unit, or the grating unit maybe formed using a liquid crystal display panel. Each of the first andsecond illumination units 312 and 314 may further include an actuator(not shown) minutely moving the grating unit.

The projecting lens may be formed, for example, by combining a pluralityof lenses, and the projecting lens focuses the first grating patternlight or the second grating pattern light generated by the grating uniton the measurement target 20.

The camera section 320 is disposed over the base board 10 to photographreflection light reflected by the measurement target 20. In other words,the camera section 320 may capture the first grating pattern light orthe second grating pattern light reflected by the measurement target 20.The camera section 320 may be disposed at the middle of between thefirst and second illumination units 312 and 314.

The camera section 320 may include, for example, a camera unit (notshown) capturing the first grating pattern light or the second gratingpattern light and a receiving lens (not shown) focusing the firstgrating pattern light or the second grating pattern light to provide thecamera unit.

The control section 330 controls the projecting section 310 and thecamera section 320, and processes the first and second grating patternlights captured by the camera section 320 to measure a two dimensionalshape and/or a three dimensional shape.

Particularly, the control section 330 provides first and secondillumination control signals S1 and S2 to the first and secondprojecting sections 312 and 314, respectively, to thereby controlgeneration, amount, intensity, etc. of the first and second gratingpattern lights. In addition, the control section 330 provides the camerasection 320 with a photographing control signal Con, to thereby controlthe camera section 320 to capture the first and second grating patternlights at a proper timing, and receives data Dat including the capturedgrating pattern light from the camera section 320.

The three dimensional shape measurement apparatus 300 may also measure alarge area measurement target (not shown) having a relatively largearea, as is different from in FIG. 5. In order to measure a threedimensional shape of the large area measurement target, the large areameasurement target may need to be divided into a plurality ofmeasurement areas. In other words, the three dimensional shapemeasurement apparatus 300 measures and combines three dimensional shapesfor the measurement areas, to thereby measure a three dimensional shapeof the large area measurement target. Thus, the three dimensional shapemeasurement apparatus 300 photographs an image in any one measurementarea, and then may need to photograph an image in another measurementarea.

When the image in the “one measurement area”, which is photographed in aprevious timing is defined as “previous image”, and the image in the“another measurement area”, which is photographed in a next timing isdefined as “present image”, the three dimensional shape measurementapparatus 300 arithmetically processes the previous image, which isalready photographed, by using a plurality of central processing unitswhile photographing the present image. For example, the control section330 may include first and second central processing units CPU1 and CPU2to arithmetically process the previous image while photographing thepresent image.

FIGS. 6 and 7 are block diagrams illustrating a method of arithmeticallyprocessing multiple images according to an exemplary embodiment of thepresent invention. Particularly, FIG. 6 illustrates a process ofarithmetically processing multiple images by using two centralprocessing units CPU1 and CPU2, and FIG. 7 illustrates a process ofarithmetically processing multiple images by using three centralprocessing units CPU1, CPU2 and CPU3.

In an exemplary embodiment, the three dimensional shape measurementapparatus is substantially the same as the three dimensional shapemeasurement apparatus 300 in FIG. 5, and thus any further descriptionwill be omitted.

Referring to FIG. 6, in an exemplary embodiment, the measurement targetmay be measured with being divided into a plurality of measurement areasFOV1, FOV2, FOV3, FOV4, . . . , etc. For example, the three dimensionalshape measurement apparatus measures a three dimensional shape in afirst measurement area FOV1, and then a measurement target area is movedto a second measurement area FOV2. Thereafter, the three dimensionalshape measurement apparatus measures a three dimensional shape in thesecond measurement area FOV2, and then the measurement target area ismoved to a third measurement area FOV3. As described above, the threedimensional shape measurement apparatus may repeat measurement for thethree dimensional shape and movement of the measurement target area foreach measurement area.

In a method of arithmetically processing multiple images according to anexemplary embodiment of the present invention, firstly, a first image isphotographed in the first measurement area FOV1 of the measurementtarget by using the three dimensional shape measurement apparatus. Thefirst image may include a plurality of way images that are photographedwith respect to the measurement target in different directions. Forexample, the first image may include first and second way images. Thefirst way image is formed by the light from the first illumination unit312 in FIG. 5, and the second way image is formed by the light from thesecond illumination unit 314 in FIG. 5.

After the first image is photographed in the first measurement areaFOV1, the first image is arithmetically processed by the first centralprocessing unit CPU1. A method of arithmetically processing the firstimage may include a step of arithmetically processing the first wayimage, a step of arithmetically processing the second way image, and astep of merging the first and second way images. The first centralprocessing unit CPU1 may be included in the control section 330 in FIG.5.

While the first central processing unit CPU1 arithmetically processesthe first image, the measurement target area of the three dimensionalshape measurement apparatus is moved from the first measurement areaFOV1 to the second measurement area FOV2, and a second image isphotographed in the second measurement area FOV2. The second image mayinclude two way images, which is the same as the first image.

After the second image is photographed in the second measurement areaFOV2, the second image is arithmetically processed by the second centralprocessing unit CPU2 that is different from the first central processingunit CPU1. A method of arithmetically processing the second image issubstantially the same as the method of arithmetically processing thefirst image.

While the second central processing unit CPU2 arithmetically processesthe second image, the measurement target area of the three dimensionalshape measurement apparatus is moved from the second measurement areaFOV2 to the third measurement area FOV3, and a third image isphotographed in the third measurement area FOV3. The third image mayinclude two way images, which is the same as the first and secondimages.

Meanwhile, in an exemplary embodiment, a process that the first centralprocessing unit CPU1 arithmetically processes the first image isfinalized before photographing the third image is completed.

After the third image is photographed in the third measurement areaFOV3, the first central processing unit CPU1 arithmetically processesthe third image. A method of arithmetically processing the third imageis substantially the same as the method of arithmetically processing thefirst and second images.

As described above, a plurality of images is measured while themeasurement target area of the three dimensional shape measurementapparatus is moved for each measurement area, and the images may bedivided and arithmetically processed by using the first and secondcentral processing units CPU1 and CPU2. In other words, the firstcentral processing unit CPU1 may arithmetically process imagesphotographed in odd numbered measurement areas, and the second centralprocessing unit CPU2 may arithmetically process images photographed ineven numbered measurement areas.

Referring to FIG. 7, the images photographed in the measurement areas ofthe measurement target may be image-processed by using three centralprocessing units CPU1, CPU2 and CPU3. In other words, the first centralprocessing unit CPU1 may arithmetically process images photographed in1, 4, 7, . . . , etc. numbered measurement areas, the second centralprocessing unit CPU2 may arithmetically process images photographed in2, 5, 8, . . . , etc. numbered measurement areas, and the third centralprocessing unit CPU3 may arithmetically process images photographed in3, 6, 9, . . . , etc. numbered measurement areas. As a result, the firstcentral processing unit CPU1 may arithmetically process the first imagephotographed in the first measurement area FOV1, from a time thatphotographing in the first measurement area FOV1 is finished to a timethat photographing in the fourth measurement area FOV4 is finished. Inaddition, the second and third central processing units CPU1 and CPU2may arithmetically process an image in each measurement area forsubstantially the same time as a time for which the arithmetical processof the first central processing unit CPU1 is possible.

In FIGS. 6 and 7, the image for each measurement area is arithmeticallyprocessed by using two or three central processing units. Alternatively,the image for each measurement area may be arithmetically processed byusing four or more central processing units.

FIG. 8 is a block diagram illustrating a process of arithmeticallyprocessing multiple images by using a single central processing unit.

Referring to FIG. 8, when the multiple images photographed in eachmeasurement area are arithmetically processed by using a single centralprocessing unit CPU, measurement time may be lengthened in measuring thethree dimensional shape of the measurement target. That is, as thesingle central processing unit CPU arithmetically processes all theimages photographed in each measurement area, the three dimensionalshape measurement apparatus may have a waiting time betweenphotographing processes for the measurement areas. Thus, measurementtime for photographing the three dimensional shape of the measurementtarget may be lengthened.

However, in the present embodiment, the image of each measurement areais arithmetically processed by using the plurality of central processingunits, and thus the waiting time between photographing processes for themeasurement areas may be removed, to thereby reduce a time for measuringthe three dimensional shape of the measurement target.

FIG. 9 is a block diagram illustrating a method of arithmeticallyprocessing multiple images according to an exemplary embodiment of thepresent invention.

The method of arithmetically processing multiple images in FIG. 9 issubstantially the same as the method of arithmetically processingmultiple images described in FIG. 6 except for the arithmetical processof the first and second central processing units CPU1 and CPU2. Thus,any further description except for the arithmetical process of the firstand second central processing units CPU1 and CPU2 will be omitted.

Referring to FIG. 9, a first central processing unit CPU1 arithmeticallyprocesses a portion of the image photographed in each measurement area,and a second central processing unit CPU2 arithmetically processes aremaining portion of the image. For example, the first centralprocessing unit CPU1 arithmetically processes a portion of the firstimage photographed in the first measurement area, and the second centralprocessing unit CPU2 arithmetically processes a remaining portion of thefirst image.

In an exemplary embodiment, the image photographed in each measurementarea includes first and second way images photographed in differentdirections, and thus the first central processing unit CPU1 mayarithmetically process the first way image, and the second centralprocessing unit CPU2 may arithmetically process the second way image.One of the first and second central processing units CPU1 and CPU2arithmetically processes merging of arithmetically processed data forthe first and second way images.

According to the present embodiment, when the image photographed in eachmeasurement area includes a plurality of way images, central processingunits, the number of which is the same as the number of the way images,arithmetically process the way images, respectively. Thus, measurementtime for the three dimensional shape of the measurement target may bereduced.

FIG. 10 is a block diagram illustrating a method of arithmeticallyprocessing multiple images according to an exemplary embodiment of thepresent invention.

The method of arithmetically processing multiple images in FIG. 10 issubstantially the same as the method of arithmetically processingmultiple images described in FIG. 6 except for the arithmetical processof the first and second central processing units CPU1 and CPU2. Thus,any further description except for the arithmetical process of the firstand second central processing units CPU1 and CPU2 will be omitted.

Referring to FIG. 10, the image photographed in each measurement area isdivided into a plurality of segments, and the divided segments arearithmetically processed by a plurality of central processing units.

For example, when the image photographed in each measurement areaincludes first and second way images photographed in differentdirections, arithmetical process for each of the first and second wayimages may be divided into eight segments F1, F2, F3, F4, F5, F6, F7 andF8. The first central processing unit CPU1 may arithmetically processodd numbered segments F1, F3, F5 and F7, and the second centralprocessing unit CPU2 may arithmetically process even numbered segmentsF2, F4, F6 and F8.

The process of merging arithmetically processed data for the first andsecond way images may also be divided into a plurality of segments. Forexample, the process of merging may be divided into four segments M1,M2, M3 and M4. The first central processing unit CPU1 may merge thefirst and third segments M1 and M3, and the second central processingunit CPU2 may merge the second and fourth segments M2 and M4.

According to the present embodiment, the image photographed in eachmeasurement area is divided into a plurality of segments, and aplurality of central processing units arithmetically processes thesegments. Thus, measurement time for the three dimensional shape of themeasurement target may be reduced.

FIG. 11 is a schematic view illustrating a board inspection apparatusaccording to an exemplary embodiment of the present invention.

Referring to FIG. 11, a board inspection apparatus 500 according to anexemplary embodiment of the present invention includes a stage 540supporting and moving a board 550 on which a measurement target isformed, at least one projecting section 510 illuminating a gratingpattern light onto the board 550, and a camera 530 photographing areflection grating image reflected by the board 550. In addition, theboard inspection apparatus 500 may further include an illuminatingsection 520 disposed adjacent to the stage 540 to illuminate a lightonto the board 550 independently of the projecting section 510.

The projecting section 510 illuminates the grating pattern light foracquiring three dimensional information such as height information,visibility information, etc. onto the board 550 in order to measure athree dimensional shape of the measurement target formed on the board550. For example, the projecting section 510 includes a light source 512generating a light, a grating element 514 converting the light from thelight source 512 into the grating pattern light, a grating-movinginstrument 516 pitch-moving a grating element 514 and a projecting lens518 projecting the grating pattern light converted by the gratingelement 514 onto the measurement target. The grating element 514 may bemoved using a grating-moving instrument 516 such as a piezoelectric(PZT) actuator by 2π/n per one time and n−1 times in total, for phasetransition of the grating pattern light. The ‘n’ is a natural numbergreater than or equal to 2. A plurality of projecting sections 710 maybe disposed apart from each other by a substantially constant angle withrespect to the center of the camera 530 so as to increase inspectionaccuracy.

The illuminating section 520 may have a circular ring shape, andinstalled adjacent to the stage 540. The illuminating section 520illuminates a light onto the board 550 to set up an initial alignment,an inspection area, etc. of the board 550. For example, the illuminatingsection 520 may include a fluorescent lamp generating white light or alight emitting diode (LED) including at least one of a red LED, a greenLED and a blue LED generating red light, green light and blue light,respectively.

The camera 530 photographs the reflection grating image of the board 550by the grating pattern light from the projecting section 510, and areflection image of the board 550 by the light from the illuminatingsection 520. For example, the camera 530 may be disposed over the board550.

In an exemplary embodiment, the camera 530 may employ a camera having arolling shutter mode using a CMOS sensor. The camera 530 having arolling shutter mode does not photograph a snapshot of a total image forone frame of the measurement target, but sequentially scans an image forone frame of the measurement target by a line or a row from up to downto acquire image data.

The board inspection apparatus 500 having the above structureilluminates the light onto the board 550 by using the projecting section510 or the illuminating section 520, and the image of the board 550 isphotographed by using the camera 530, to thereby measure a threedimensional image and a two dimensional image of the board 550. Theboard inspection apparatus 500 illustrated in FIG. 11 is just anexample, and the board inspection apparatus 500 may be variouslymodified to include one or more projecting section and camera.

Hereinafter, a method of inspecting a board by using the boardinspection apparatus 500 having the above structure will be described indetail.

FIG. 12 is a time chart illustrating a method of inspecting a boardaccording to an exemplary embodiment of the present invention. In FIG.12, a method of inspecting a board using one projecting section and acamera having a rolling shutter mode is described.

Referring to FIGS. 11 and 12, in order to photograph an image of themeasurement target formed on the board 550, the camera 530 sequentiallyopens a shutter for each line from a first line 610 to a last line 620of pixels arranged in a matrix form for one frame, to receive thereflection grating image reflected by the board 550. That is, a CMOSimage sensor has an electronic shutter function, and since the functioncorresponds to a rolling shutter mode in which two dimensionallyarranged pixels are sequentially scanned for each line and signalsthereof are acquired, exposure time is different per line. Thus, theshutter of the camera 530 is opened later from the first line 610 to thelast line 610. For example, it is delayed by a rolling time RT, from anopen time P0 of the first line 610 to an open time P1 of the last line620.

The projecting section 510 illuminates the grating pattern light ontothe measurement target for a predetermined first time interval t1existing between a first time P1 at which the shutter for the last line620 is opened and a second time P2 at which the shutter for the firstline 610 is closed. In other words, the light source 512 included in theprojecting section 510 generates a light for the first time interval t1,and the light generated from the light source 512 is converted into agrating pattern light by the grating element 514 to illuminate themeasurement target formed on the board 550.

When a light is illuminated for the rolling time RT corresponding to atime interval between the open time P0 at which the shutter for thefirst line 610 is opened and the first time P1 at which the shutter forthe last line 620 is opened, the camera 530 may not perfectly photographa total image for one frame. Thus, the grating pattern light may beilluminated at a time except the rolling time RT, to thereby maintainmeasurement quality. In addition, in order to maintain measurementquality and allow measurement time to be as short as possible, forexample, the projecting section 510 illuminates the grating patternlight onto the measurement target for the first time interval t1 fromthe first time P1 at which the shutter for the last line 620 is opened.The first time interval t1 indicates at least time for which the camera530 may sufficiently photograph an image for one frame. The projectingsection 510 may illuminate the grating pattern light onto themeasurement target for a time longer than the first time interval t1.

When photographing the reflection grating image is completed for oneframe by once illuminating the grating pattern light, the gratingelement 514 is moved using the grating-moving instrument 516 by 2π/n,and the reflection grating image is photographed for a next frame. The‘n’ is a natural number greater than or equal to 2.

In order to reduce inspection time, the grating element 514 is moved fora time interval for which the shutter is opened from the first line 610to the last line 620. For example, the grating element 514 is moved fora second time interval t2 between a third time P3 at which illuminationof the projecting section 510 is completed and a fourth time P4 at whichthe shutter for the last line 620 is closed. In other words, the gratingelement 514 is moved by using a time for which the light source 512 doesnot generate light and the rolling time RT of the shutter. In otherwords, the grating element 514 is not moved for a time interval forwhich all the lines of the camera 530 simultaneously receive thereflection grating image. Generally, the second time interval t2 forwhich the grating element 514 is once moved by using the grating-movinginstrument 516 such as a piezoelectric (PZT) actuator is greater thanthe first time interval t1 for which illumination is performed foracquiring an image, and is greater than or equal to the rolling time RTof the camera 530.

Thus, a time required to photograph an image for one frame correspondsto a time of the first time interval t1 for which the projecting section510 illuminates the grating pattern light, added to the second timeinterval t2 for which the grating element 514 is moved.

Meanwhile, since the board inspection apparatus 500 employs an n-bucketalgorithm, the grating element 514 is moved by 2π/n per one time and n−1times in total, and the camera 530 receives the reflection grating imageby n times corresponding to the movement of the grating element 514.

As described above, in photographing a plurality of phase-transitedimages while the grating element 514 is moved by using one projectingsection 510 and the camera 530, the grating element 514 is moved for therolling time RT of the camera 530, for which an image is notsubstantially photographed, to thereby maintain measurement quality andreduce measurement time.

FIG. 13 is a time chart illustrating a method of inspecting a boardaccording to an exemplary embodiment of the present invention. In FIG.13, a method of inspecting a board by using two or more projectingsections and a camera having a rolling shutter mode is described.

Referring to FIGS. 11 and 13, in order to photograph an image of themeasurement target formed on the board 550, the camera 530 sequentiallyopens a shutter for each line from a first line 610 to a last line 620of pixels arranged in a matrix form for one frame. It is delayed by arolling time RT, from an open time P0 at which the first line 610 isopened to an open time P1 at which the last line 620 is opened.

For example, in a first frame, a first projecting section 510 acorresponding to one of at least two projecting sections 510 illuminatesa grating pattern light onto the measurement target for a first timeinterval t1 between a first time P1 at which the shutter for the lastline 620 is opened and a second time P2 at which the shutter for thefirst line 610 is closed. In other words, the light source 512 includedin the first projecting section 510 a generates a light for the firsttime interval t1, and the light generated from the light source 512 isconverted into a grating pattern light by the grating element 514 toilluminate the measurement target formed on the board 550. Theprojecting section 510 may illuminate the grating pattern light for atime interval longer than the first time interval t1 according toproduct specification.

In order to maintain measurement quality and allow measurement time tobe as short as possible, for example, the first projecting section 510 ailluminates the grating pattern light onto the measurement target forthe first time interval t1 from the first time P1 at which the shutterfor the last line 620 is opened. The first time interval t1 indicates atleast time for which the camera 530 may sufficiently photograph an imagefor one frame.

When photographing the image is completed for the first frame by usingfirst projecting section 510 a, the grating element 514 is moved and theimage is required to be photographed again. As shown in FIG. 12, whenillumination of the light source 512 and movement of the grating element514 is sequentially performed, at least time required for photographingthe image for one frame corresponds to a time for illumination of thelight source 512, added to a time for movement of the grating element514. However, in FIG. 12, when at least two projecting sections 510 areused, the images are photographed by alternately using the projectingsections 510, to thereby more reduce measurement time.

Particularly, the image for the first frame is photographed by using thefirst projecting section 510 a, and the image for the following secondframe is photographed by using another projecting section 510 except thefirst projecting section 510 a, for example, a second projecting section510 b. That is, in the second frame, the second projecting section 510 billuminates the grating pattern light onto the measurement target for afirst time interval t1 between a first time P1 at which the shutter forthe last line 620 is opened and a second time P2 at which the shutterfor the first line 610 is closed. In other words, the light source 512included in the second projecting section 510 b generates a light forthe first time interval t1, and the light generated from the lightsource 512 is converted into a grating pattern light by the gratingelement 514 to illuminate the measurement target formed on the board 550in a different direction from the first projecting section 510 a.

In order to reduce inspection time, the grating element 514 is moved fora frame interval for which the projecting section 510 does notilluminate the light. For example, a second grating element 514 includedin the second projecting section 510 b is moved for the first frame inwhich the reflection grating image is photographed using the firstprojecting section 510 a, and a first grating element 514 included inthe first projecting section 510 a is moved for the second frame inwhich the reflection grating image is photographed using the secondprojecting section 510 b. In other words, in the first frame, the secondgrating element 514 included in the second projecting section 510 b ismoved for a predetermined second time interval t2 existing between thefirst time P1 at which the shutter for the last line 620 is opened andthe third time P3 at which the shutter for the last line 620 is closed.For example, the second grating element 514 is moved for the second timeinterval t2 from the first time P1. Generally, the second time intervalt2 for which the grating element 514 is once moved by using thegrating-moving instrument 516 such as a piezoelectric (PZT) actuator isgreater than the first time interval t1 for which illumination isperformed for acquiring an image, and is greater than or equal to therolling time RT of the camera 530.

Thus, a time required to photograph an image for one frame correspondsto a time of the first time interval t1 for which the light source 512illuminates the light, added to the rolling time RT from the open timeP0 at which the first line 610 is opened to the open time P1 at whichthe last line 620 is opened.

In the present embodiment, two projecting sections 510 are employed foran example. Alternatively, when three or more projecting sections 510are employed, substantially the same inspection method may be applied.

As described above, in photographing the image of the measurement targetby using two or more projecting sections 510, the grating element 514 ismoved for a frame interval for which the associated projecting section510 does not illuminate light, to thereby maintain measurement qualityand reduce measurement time more.

FIG. 14 is a schematic view illustrating a board inspection apparatusaccording to an exemplary embodiment of the present invention. In FIG.14, a reference numeral 150 can be named for a board or an inspectionboard.

Referring to FIG. 14, a board inspection apparatus 700 according to anexemplary embodiment of the present invention includes a stage 740supporting and moving a board 750 on which a measurement target isformed, at least one projecting section 710 illuminating a pattern lightonto the board 750, and a camera 730 photographing an image of the board750. In addition, the board inspection apparatus 700 may further includean illuminating section 720 disposed adjacent to the stage 740 toilluminate a light onto the board 750 independently of the projectingsection 710.

The projecting section 710 illuminates the pattern light for acquiringthree dimensional information such as height information, visibilityinformation, etc. onto the board 750 in order to measure a threedimensional shape of the measurement target formed on the board 750. Forexample, the projecting section 710 includes a light source 712generating a light, a grating element 714 converting the light from thelight source 712 into the pattern light, a grating-moving instrument 716pitch-moving a grating element 714 and a projecting lens 718 projectingthe pattern light converted by the grating element 714 onto themeasurement target. The grating element 714 may be moved using agrating-moving instrument 716 such as a piezoelectric (PZT) actuator by2π/n per one time and n times in total, for phase transition of thepattern light. The ‘n’ is a natural number greater than or equal to 2. Aplurality of projecting sections 710 may be disposed apart from eachother by a substantially constant angle with respect to the center ofthe camera 730 so as to increase inspection accuracy.

The illuminating section 720 may have a circular ring shape, andinstalled adjacent to the stage 740. The illuminating section 720illuminates a light onto the board 750 to set up an initial alignment,an inspection area, etc. of the board 750. For example, the illuminatingsection 720 may include a fluorescent lamp generating white light or alight emitting diode (LED) including at least one of a red LED, a greenLED and a blue LED generating red light, green light and blue light,respectively.

The camera 730 photographs an image of the board 750 by the patternlight from the projecting section 710, and an image of the board 750 bythe light from the illuminating section 720. For example, the camera 730may be disposed over the board 750. The camera 730 may employ a camerahaving a rolling shutter mode using a CMOS sensor. The camera 730 havinga rolling shutter mode scans two dimensionally arranged pixels by a lineunit to acquire image data. Alternatively, the camera 730 may employ acamera having a global shutter mode using a CCD sensor. The camera 730having a global shutter mode photographs a snapshot of an image within afield of view to acquire image data once.

The board inspection apparatus 700 having the above structureilluminates the light onto the board 750 by using the projecting section710 or the illuminating section 720, and the image of the board 750 isphotographed by using the camera 730, to thereby measure a threedimensional image and a two dimensional image of the board 750. Theboard inspection apparatus 700 illustrated in FIG. 14 is just anexample, and the board inspection apparatus 700 may be variouslymodified to include one or more projecting section 710 and the camera730.

Hereinafter, a method of inspecting a board by using the boardinspection apparatus 700 having the above structure will be described indetail. In an exemplary embodiment, a method of inspecting variousmeasurement targets, for example, LED bars mounted on an inspectionboard such as a jig will be described.

FIG. 15 is a flow chart illustrating a method of inspecting a boardaccording to an exemplary embodiment of the present invention. FIG. 16is a plan view illustrating an inspection board according to anexemplary embodiment of the present invention.

Referring to FIGS. 14, 15 and 16, in order to inspect a measurementtarget, the inspection board 750 on which a plurality of measurementtargets 810 is disposed is loaded to the board inspection apparatus 700in step S100. For example, a measurement target 810 may include an LEDbar on which LED chips 812 are mounted at regular intervals. Theinspection board 750 may correspond to, for example, a fixing supporter,and grooves are formed at the fixing supporter to receive themeasurement targets 810. For example, the measurement targets 810 may bedisposed on the inspection board 750 to be arranged in a plurality ofrows with a constant direction.

After the inspection board 750 is loaded to the board inspectionapparatus 700, the inspection board 750 is moved to a measurementlocation according to movement of the stage 740.

After the inspection board 750 is moved to the measurement location, theimage of the inspection board 750 is photographed by using theprojecting section 710 or the illuminating section 720 and the camera730. That is, after illuminating the pattern light onto the inspectionboard 750 by using the projecting section 710, the camera 730 capturesthe pattern light reflected by the measurement targets 810 to photographthe image of the inspection board 750. When a size of the inspectionboard 750 is large, the total area of the inspection board 750 may notbe within a field of view FOV of the camera 730. Thus, as shown in FIG.16, the inspection board 750 is divided into a plurality of areascorresponding to the field of view FOV of the camera 730, and ismeasured.

FIG. 17 is a plan view illustrating a partial image of the inspectionboard in FIG. 16, which is photographed by a camera.

Referring to FIGS. 14, 15 and 17, when a specific area of the inspectionboard 750 is photographed by using the camera 730, as shown in FIG. 17,there exist a portion in which the measurement target 810 exists and aportion in which the measurement target 810 does not exist in the fieldof view FOV of the camera 730. Thus, the board inspection apparatus 700only inspects a portion in which the measurement targets 810 existexcept a portion in which the measurement targets 810 do not exist, tothereby reduce measurement time.

Particularly, the board inspection apparatus 700 divides inspectionareas (window of interest) WOI in which the measurement targets 810 arelocated in the field of view FOV of the camera 730 to acquire image datafor each the inspection area WOI in step S110. The inspection area WOIis determined to be at least same as the measurement target 810 or alittle larger than the measurement target 810 so as to measure themeasurement target 810. As the inspection area WOI is larger, image datafor being processed increases, and thus the inspection area WOI isdetermined similar to a range of the measurement target 810, which issubstantially to be measured, to thereby decrease data for beingprocessed and reduce data processing time.

The inspection area WOI is determined before acquiring the image data.For example, the inspection area WOI may be determined by a method inwhich a user himself inputs a location of the measurement target 810 onthe inspection board 750 to the board inspection apparatus 700.Alternatively, the inspection area WOI may be determined by teaching ofthe inspection board 750 using the board inspection apparatus 700. Thatis, the inspection board 750 loaded to the board inspection apparatus700 is photographed through the camera 730 to distinguish an area inwhich the measurement target 810 exists, and determine the distinguishedarea as the inspection area WOI. The information for the inspection areaWOI obtained as the above may be used to basic data for mappingperformed later.

A method of acquiring the image data may be various according to sortsof the camera 730.

For example, the camera 730 may employ a camera having a rolling shuttermode using a CMOS image sensor. The camera 730 having a rolling shuttermode sequentially scans two dimensionally arranged pixels by a line unitto acquire image data. The camera 730 having a rolling shutter mode doesnot scan the entire area of the field of view FOV of the camera 730, butonly scans the determined inspection areas WOI by a line unit to acquirethe image data for each inspection area WOI.

As described above, the inspection area WOI is selectively scanned inthe field of view FOV of the camera 730 through the camera 730 having arolling shutter mode to acquire the image data for the measurementtarget 810, thereby reducing scanning time of the camera 730 and totalphotographing time of the camera 730.

Alternatively, the camera 730 may employ a camera having a globalshutter mode using a CCD image sensor. The camera 730 having a globalshutter mode photographs a snapshot of a total area of the field of viewFOV to selectively acquire the image data for the inspection areas WOIout of the total area of the field of view FOV.

After acquiring the image data for each inspection area WOI, shapes ofthe measurement targets 810 are inspected by using the image data instep S120.

In inspecting the measurement target 810, one measurement target 810 isdivided into a plurality of areas to be photographed, according to thefield of view FOV of the camera 730. Thus, the photographed images foreach area are combined to form a total image of the measurement target810.

Particularly, in dividing the inspection board 750 into a plurality offield of views FOV and photographing the field of views FOV, the boardinspection apparatus 700 photographs the field of views FOV to be alittle overlapped, and the photographed images are mapped to form thetotal image of the measurement target 810.

In mapping the images, the image data are compared with each other in anoverlapped area to form an image of a boundary portion between the fieldof views FOV. In mapping the images, the image data with respect to anentire area of the overlapped area are not compared, but the image dataonly corresponding to the inspection areas WOI are compared. In otherwords, the images are mapped using the image data for each inspectionarea WOI, which are acquired by measuring the inspection areas WOI.

As described above, in mapping the images with respect to the overlappedarea between the field of views FOV of the camera 730, the image dataonly corresponding to the inspection area WOI, not a total area, arecompared, to thereby decrease data for being processed, and reduce dataprocessing time.

The measurement target 810 is inspected using the image data for thetotal image of the measurement target 810, which are acquired by theabove described image-mapping. For example, in case that the measurementtarget 810 is an LED bar, it is inspected that an LED chips 812 areaccurately mounted on the board.

The above described method of inspecting a board may be applied to acase that an area for inspection is separated on one board, in additionto a case that the measurement targets are separately mounted on aninspection board.

As described above, in measuring an inspection board on which aplurality of measurement targets is mounted, an inspection area in whichthe measurement targets are located is only selectively measured, tothereby reduce photographing time of a camera. In addition, since imagedata of the inspection area only are used, data for being processed aredecreased, and especially, data for comparison in mapping images aredecreased to greatly reduce measurement time.

It will be apparent to those skilled in the art that variousmodifications and variation can be made in the present invention withoutdeparting from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. A three dimensional shape measurement apparatuscomprising: m projecting sections, each of which includes a light sourceand a grating element, and, while moving the grating element by n times,projects a grating pattern light onto a measurement target for eachmovement, wherein the ‘n’ and the ‘m’ are natural numbers greater thanor equal to 2; an imaging section photographing a grating pattern imagereflected by the measurement target; and a control section controllingthat, while photographing the grating pattern image by using one of them projecting sections, a grating element of the one of the m projectingsections is not moved and a grating element of at least anotherprojecting section is moved.
 2. The three dimensional shape measurementapparatus of claim 1, when the m is 2, wherein while photographing thegrating pattern image by one time by using a first projecting section,the control section moves the grating element having a periodicstructure of a second projecting section by 1/n of a period of theperiodic structure, and then while photographing the grating patternimage by one time by using the second projecting section, the controlsection moves the grating element of the first projecting section by 1/nof the period of the periodic structure.
 3. The three dimensional shapemeasurement apparatus of claim 1, when the m is greater than or equal to3, wherein the control section photographs the grating pattern image bym times by using the projecting sections for one time respectively, froma first projecting section to an m-th projecting section, and a gratingelement having a periodic structure of a projecting section that is notused for the photographing time of the m times is moved by 1/n of aperiod of the periodic structure for non-photographing time.
 4. Thethree dimensional shape measurement apparatus of claim 3, wherein thecontrol section controls that each projecting section moves the gratingelement thereof before at least two photographing times prior toprojecting the grating pattern light.
 5. The three dimensional shapemeasurement apparatus of claim 1, wherein the control section controlsthat the grating pattern image is photographed by using one projectingsection of the m projecting sections, and then for immediately followingphotographing time of another projecting section, a grating element ofthe one projecting section is moved.